The present invention relates to a method and device for controlling the drive train of a motor vehicle during gear shift operations.
In vehicles having an automated gear box and an electronically actuated clutch, an automated gear change occurs by triggering the internal combustion engine, clutch, and transmission components. These components must be actuated appropriately such that the gear change occurs as quickly and therefore as comfortably as possible.
Conventional methods for determining the target transmission gear which, besides the direct input variables, also take into account the driving situation, the driver type, and operating conditions when determining the gear. These methods are described in, for example, German Published Patent Application No. 196 25 935 or German Published Patent Application No. 197 03 863.
Moreover, systems for coordinated drive train control are conventional. German Published Patent Application No. 199 37 455 describes a system for controlling the assemblies in gear shift operations that is embedded in a system for controlling the drive train.
However, the conventional methods do not guarantee an optimal control of the shift operation with regard to traction and comfort while taking into account the driving situation, driver type, and operating conditions.
An object of the present invention is to provide an optimal control of the assemblies of the drive train during gear shift operations with regard to traction and comfort under all operating conditions.
As described above, the present invention relates to the coordinated control of the elements servo clutch, vehicle engine, and transmission arranged in the drive train of a motor vehicle during a change in the gear ratio. In accordance with the present invention, temporal progressions of the states of the vehicle engine and the servo clutch may be established for the change in gear ratio. The control of the servo clutch and the vehicle engine during the change in gear ratio then may occur in such a manner that the servo clutch and the vehicle engine assume the states according to the established temporal progressions.
Thus, according to the present invention, an optimal system trajectory for the shift operation may be determined for the conditions of the internal combustion engine and the clutch and this trajectory may be supplied to a subordinate control and regulation. The determination of the optimal system trajectory may occur in this connection as a function of the stipulations of a higher-order system for controlling the drive train.
According to an example embodiment of the present invention, provision is made that, during driving operation of the vehicle, at least
one driver type value representative of the behavior of the driver of the vehicle and/or
one driving situation value representative of the instantaneous driving situation and/or
one operating state value representative of the operating state of at least one element of the drive train and/or
one operating condition value representative of at least one operating condition of at least one element of the drive train is calculated. The temporal progressions may then be determined dependent upon at least one of the calculated values. Thus, it may also be provided according to the present invention for the optimal system trajectory to be adapted to the driving situation, driver type, operating conditions of the assemblies and the state of the assemblies themselves.
The determination of the optimal system trajectory may occur via a real-time optimization algorithm that may be executed during driving operation. This means that the temporal progressions may be calculated and updated during driving operation. At the beginning of a change in the gear ratio, the respective updated progressions may then be established as the progressions according to which the control of the servo clutch and of the vehicle engine occurs during the change in the gear ratio.
In particular, a result of this algorithm may include the target progression of the engine speed and the target progression of the clutch output torque. This means that the output speed of the vehicle engine may be set as the state of the vehicle engine and the output torque of the servo clutch may be set as the state of the servo clutch.
Using the present invention, optimal shift operation may be attained under all operating conditions that may provide a high degree of comfort with a low loss of traction.